Changes to function arguments

[sallen12]

Main changes are:

• Add an additional argument to the CRPS, energy score, variogram score, and Gaussian kernel scores (and weighted versions) that allows different ensemble members to have different weights.
• Add a weight argument to the variogram score to emphasise different pairs of dimensions.
• Add parameter checks when calculating the CRPS and log score for parametric distributions. An additional argument "check_pars" is added to the score functions, so that the checks can be removed for more efficient optimisation of the scores as loss functions.
• Adapt order of parameter arguments when calculating the CRPS and log score. The parameters can now be input positionally.